Field
Embodiments of the present invention relate to the field of clinical diagnostic tools.
Background
Whole blood is widely used in in-vitro diagnostic research. Blood tests can provide valuable information for clinical diagnosis and drug development. However, most blood is analyzed using the blood plasma or serum, because red blood cells and their constituent substances (blood cell containing components) can interfere with the measurement. Thus, separation of serum or plasma from whole blood is a typical preparation step for blood analysis.
Conventionally, serum or plasma separation is performed by centrifugation using commercially available bench-top devices. This process is laborious and time-consuming, and the integration of centrifugal systems in small point-of-care devices is challenging and size-limited. Hence, other separation techniques are under development which allow for integration into point-of-care devices. Such techniques are based on the principles of electro-osmotic flow, hydrodynamic separations, acoustic forces, dielectrophoresis and particle retention. The latter separation principle normally relies on asymmetric membranes, which block red blood cells from passing such a filter. Plasma filtration is a promising plasma separation method, but has many drawbacks or challenges to overcome. Drawbacks are related to filter/membrane integration, clogging, plasma re-collection from the membrane and undesirable filtering of biomolecules. Further, filtration is time consuming and blood with a high hematocrit has to be diluted.
Electro-osmotic flow and hydrodynamic separations principles are used for microfluidic devices with analyte volumes in the micro-liter range. However, such techniques exhibit less plasma separation efficiency than centrifugation-based techniques.